The new Berberis cultivar is a product of a planned breeding program conducted by the inventor, Thomas Ranney, in Mills River, N.C. The objective of the breeding program was to produce new Berberis varieties with purple foliage, compact plant forms and low fertility. The cross resulting in this new variety was made during Spring of 2005.
The seed parent is an unpatented, unnamed Berberis thunbergii var. atropurpurea. The pollen parent is also an unpatented, unnamed Berberis thunbergii var. atropurpurea. Seed collected from this crossing was treated with ethyl methanesulfonate, to increase the likelihood of mutation. The new variety was identified as a potentially interesting selection in Summer of 2006, at a research nursery in Mills River, N.C.
Asexual reproduction of the new cultivar ‘NCBT1’ by stem cuttings was first performed during the Summer of 2007, at a research nursery in Mills River, N.C. Subsequent propagation has shown that the unique features of this cultivar are stable and reproduced true to type in three successive generations.